Sustainability overview

The latest stock assessment was undertaken in 2016 and results were very similar to previous assessments, indicating that the stock is not overfished nor being subject to overfishing. The skipjack catch in 2017 (1,624,162t) was the lowest since 2011, and below the 2012-2016 average of 1,835,751 t and below estimated maximum sustainable yield of 1,892,000t. The commission is looking to establish harvest strategies for key fisheries and stocks but has not yet completed this work and so, as of January 2018 adopted a bridging measure to manage bigeye, yellowfin and skipjack until harvest strategies are in place or February 2021. As part of this, the average spawning biomass for skipjack is to be maintained at the interim target of 50% of unfished levels (about current levels). There is no Total Allowable Catch (TAC) set for this stock, but as skipjack is caught alongside bigeye and yellowfin, primarily in purse seine fisheries (nearly half of which is set on FADs), the range of measures and capture method impacts listed for bigeye also apply to skipjack and includes limits on vessel days and 5months of closures for purse seine sets on Fish Aggregation Devices (FADs). Economic factors and technical advances in the purse seine fishery have seen a gradual decline in the number of vessels in the pole and line fishery, which now accounts for approximately 8% of the skipjack catch. Pole and line catch in 2017 (123,132 t) was a 21% decrease from 2016. Pole and line fishing is a very labour intensive yet selective method of fishing, having little bycatch, yet considerable amounts of bait fish are used in these fisheries to attract the skipjack. The total catch of bait fish in pole & line fisheries is generally considered low compared to targeted fisheries for these species and is unlikely to overexploit these stocks, but could have implications for local availability.

Commercial buyers should establish what measures the flag state and fleet relating to their source is taking to improve monitoring and data collection and encourage development of a harvest strategy for skipjack. Large buyers should consider supporting such improvements. There is an MSC certified fishery within the scope of this rating which represents the best choice and there is also a Fishery Improvement Project (FIP) that is making progress at improving elements of the fishery. More info about this FIP is available from fisheryprogress.org.

Biology

Tuna belong to the family Scombridae. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Skipjack tuna are found throughout the world’s tropical and warm temperate waters. During the day they school on the surface (often with birds, drifting objects, sharks, whales etc.) but at night can descend to depths of 260m. Skipjack tuna are a very fast growing species, maturing at 2 to 3 years old (40cm in length) and living for up to 12 years. They can grow up to 100cm and 34kg in weight but are rarely found larger than 80cm and 10kg. They spawn all year round and have a medium to high resilience to fishing.

Stock information

Stock Area

Western and Central Pacific

Stock information

The Western and Central Pacific Ocean (WCPO) skipjack stock supports the largest tuna fishery in the World, accounting for approximately 38% of worldwide tuna landings. It is managed and assessed by the Western and Central Pacific Fisheries Commission (WCPFC).

Skipjack tuna catches in the WCPO increased steadily from 1970 onwards, roughly doubling during the 1980s. After stabilising at around 1,000,000t during the early 1990s, they increased to between 1.5 and 2 million t from 2007 and a record catch of around 2 million t was taken in 2014. The increase in fishing mortality since the 1980s has been due to the increase of catches of both juvenile and adult fish from both associated purse seine sets and the mixed gear fisheries in the Philippines and Indonesia. Biomass also increased from the early 1980’s, resulting from higher recruitments, then fluctuated and declined slightly up until 2012. Since then there appears to have been a strong increase in spawning biomass, peaking in 2013/2014 at levels just below the 1980s peaks.

The skipjack catch in 2017 (1,624,162t) was the lowest since 2011, and below the 2012-2016 average of 1,835,751 t. The latest stock assessment was undertaken in 2016, indicating that the stock is not overfished (Spawning Biomass, SB, at 2.56 Bmsy) nor being subject to overfishing (Fishing mortality, F, at 0.45 Fmsy). Recent levels of spawning biomass are well above the level that will support MSY, and while there has been a steady depletion of the stock over most of the assessment period, the stock is still estimated to be healthy, and is estimated to have been at approximately 50% of unfished levels for the past decade: well above the limit reference point of 20%. Projections were updated in 2018. Under recent fishery conditions (2017 catch level for longline and other fisheries and effort level for purse seine), the skipjack stock was projected to decrease for a short period as recent relatively high recruitments move out of the stock. Predicted F2019/FMSY = 0.47, SB2019/SBF=0 = 0.45, and SB2019/SBMSY = 1.67. In the longer term, assuming long term average recruitment, modest increases in the stock were projected.

The scientific committee advise that tagging data is a critical component of the skipjack stock assessment and recommend regular large-scale tagging cruises and complementary tag recovery work continue to be undertaken in a way that provides the best possible data for stock assessment purposes. Currently, pole and line CPUE is the major indicator of abundance for assessment purposes, which in 2017 represented around 8% of the catch and continues to shrink geographically. Pole and line catch in 2017 (123,132 t) was a 21% decrease from 2016 and a 23% decrease from the average 2012-2016 catch.

Management

Most tuna stocks range across and are accessed by numerous coastal states, making harmonised and effective management of these individual stocks very difficult. As a result, intergovernmental Regional Fisheries Management Organisations (RFMOs) have been established. There are five main tuna RFMOs worldwide and it is their responsibility to carry out data collection, scientific monitoring and management of these fisheries. The tuna fisheries in the Western and Central Pacific Ocean (WCPO) are managed by the Western and Central Pacific Fisheries Commission (WCPFC). Whilst the RFMOs are responsible for the development of management and conservation measures, the degree to which they are implemented, monitored and enforced still varies significantly between coastal states. For this reason, it is important to choose tuna that has been caught by vessels that are well regulated by their flag state.

WCPFC has put in place a lower limit for the spawning biomass of bigeye, skipjack, and yellowfin tuna of 20 percent of unfished levels (SB/SBF=0, aka spawning biomass depletion ratio), below which the stock should not fall. For skipjack there is also an interim target of 50 percent of unfished levels, which was adopted in 2015 and has been reached. The scientific committee recommends reducing fishing mortality on juvenile bigeye and yellowfin in the tropics, through preventing increases in overall fishing mortality, until targets for these two stocks can be agreed. The commission is looking to establish harvest strategies for key fisheries and stocks but has not yet completed this work and so, as of January 2018, a bridging measure is in force to manage bigeye, yellowfin and skipjack - the measure lasts until harvest strategies are in place or until February 2021. As part of this, spawning biomass depletion ratios for bigeye and yellowfin are to be maintained at recent levels (the average from 2012-2015) and skipjack at 50 percent. The bridging measure includes a number of new measures and consolidates some pre-existing ones, and is outlined below.

In the tropical region, between 20 degrees North and 20 degrees South, the following applies:The use and deployment of FADs is prohibited for 5 months of the year (3 months for Kiribati and the Philippines). VMS polling frequency increases to every 30 minutes during the FAD closure.Effort limits (in vessel days) apply to purse seining on the high seas (excluding Small Island Developing States, SIDS): limits vary by country. In order not to undermine the effectiveness of this, countries cannot transfer effort into areas outside of this region.To create an incentive to reduce the non-intentional capture of juvenile fish, to discourage waste and to encourage an efficient utilization of fishery resources, purse seiners must retain on board and then land or transship at port all bigeye, skipjack, and yellowfin tuna (also applies to national waters).All purse seine vessels operating on the high seas or within national waters in this region must carry an observer. This also applies to purse seiners anywhere in the convention area fishing in waters under multiple countries’ jurisdiction or moving between the high seas and national waters.The number and capacity of large (over 24m) purse seiners and longliners (with freezing capacity and ice-chilled) operating in this area is frozen to 2016 levels (excluding SIDs and Indonesia).

Other measures that apply to the wider convention area:The number of drifting FADs with activated instrumented buoys deployed at any one time is limited to 350 per purse seine vessel.Catch and/or effort limits apply for purse seining within national waters (both the type of limit and the amount vary by country).There are country-specific limits on longline bigeye catch, and by 2020 hard limits for bigeye and a framework to allocate them amongst countries shall be developed.Catches by other commercial tuna fisheries for bigeye, yellowfin or skipjack tuna (excluding those taking less than 2,000 tonnes) shall not exceed either the average level for the period 2001-2004 or the level of 2004.

More generally:There is a requirement to submit FAD management plans, including information on strategies used to implement closures and other measures for reducing mortality of juvenile bigeye. A number of aspects in the bridging measure have been brought forward from previous management measures, and it isn’t clear how well they have been implemented, especially given the ongoing increases in total catch of skipjack. The scientific committee recommends more comprehensive data collection relating to FADs.Observer coverage on purse seiners is poor in areas not specified in the bridging measure and only 5% coverage is required on longliners greater than 20m in length. 20% is considered to be the minimum to be effective.To help address IUU, the WCPFC maintains an IUU Vessel List, prohibits transhipments at sea between purse seiners (some exemptions apply) and requires all other transhipments to be documented and 100% observed as part of the regional observer programme.In 2017 a Compliance Monitoring Scheme was introduced to assess and improve compliance with obligations, and penalise non-compliance.

Capture Information

The Western and Central Pacific Ocean (WCPO) supports the largest skipjack tuna fishery in the world. Economic factors and technical advances in the purse seine fishery have seen a gradual decline in the number of vessels in the pole and line fishery, which now accounts for approximately 8% of the skipjack catch. Pole and line catch in 2017 (123,132 t) was a 21% decrease from 2016 and a 23% decrease from the average 2012-2016 catch. Pole and line fishing is a very labour intensive yet selective method of fishing, having little bycatch, yet considerable amounts of bait fish are used in these fisheries to attract the skipjack. Whilst bait fish are usually small, resilient species, it is important that these stocks are monitored and some basic management applied.

Alternatives

Based on method of production, fish type, and consumer rating:
only fish rated 2 and below are included as an alternative in
the list below. Click on a name to show the sustainable options
available.

Wild capture criterion scoring overview

This system has been developed by the Marine Conservation Society to help consumers choose the most environmentally sustainable fish. For
full details, please see the full wild-capture methodology available here.

Capture method and ecological effects

Score

Impact

0

Very low impact

0.25

Low impact

0.5

Some or moderate impact

0.75

High impact

1

Very high impact or illegal

Where environmental concerns from any one criteria are so great, a ‘critical fail’ may be triggered and the fishery awarded a default red
rating. For full details, please see the full wild-capture methodology available here.

WCPFC, 2018. Conservation and Management Measures of the Western and Central Pacific Fisheries Commission. Available at https://www.wcpfc.int/conservation-and-management-measures [Accessed on 06.12.2018].

WCPFC, 2018. Estimates of Annual Catches in the WCPFC Statistical Area WCPFC-SC14-2018 ST-IP-01 for the Fourteenth Regular Session of the Scientific Committee of the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, 8-16 August 2018, Busan, Republic of Korea. 34 pp. Available at https://www.wcpfc.int/meetings/14th-regular-session-scientific-committee [Accessed on 06.12.2018].

WCPFC, 2018. Summary Report of the Fourteenth Regular Session of the Scientific Committee of the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, 8-16 August 2018, Busan, Republic of Korea. 34 pp. Available at https://www.wcpfc.int/meetings/14th-regular-session-scientific-committee [Accessed on 06.12.2018].

What’s a sustainability range?

The sustainability of fish can vary significantly depending on how and where it has been caught or farmed. Many single species are caught or farmed in a variety of ways and this range shows that, within a species, some sources may be more sustainable than others.

To find out specific ratings, click on the 'Show options for this fish' button under the image of the fish.

'Best choices' are rated 1 and 2 (green), 'Fish to Avoid' are rated 5 (red). Ratings 3 and 4 mean 'Think' (yellow and amber), as there are better rated alternatives.

Fish that are under review are shown with a question mark icon and no rating.

This system has been developed by the Marine Conservation Society to help consumers and businesses choose the most environmentally sustainable fish.

To be assessed

Seafood sources indicated as, 'To be assessed', are those that have not yet been assessed and assigned a rating or are undergoing a period
of review. These include sources previously rated by MCS for which the rating has lapsed, due to changes in the market or MCS priorities and
resources. Given that these sources are not fully assessed, the profile should not be used to infer the current sustainability of the
fishery or farmed species.

If you are interested in the sustainability of this seafood source, please let us know by emailing
ratings@mcsuk.org

Rating 1

Rating 1 (light green) is associated with the most
sustainably produced seafood.

This system has been developed by the Marine Conservation
Society to help consumers choose the most environmentally
sustainable fish.

Rating 3

Rating 3 (yellow) based on available information; these
species should probably not be considered sustainable at
this time. Areas requiring improvement in the current
production may be significant. Eat only occasionally and
check www.goodfishguide.org for specific details.

This system has been developed by the Marine Conservation
Society to help consumers choose the most environmentally
sustainable fish.

Rating 4

Rating 4 (orange) should not be considered sustainable, and
the fish is likely to have significant environmental issues
associated with its production. While it may be from a
deteriorating fishery, it may be one which has improved from
a 5 rating, and positive steps are being taken. However, MCS
would not usually recommend choosing this fish.

This system has been developed by the Marine Conservation
Society to help consumers choose the most environmentally
sustainable fish.

Red Improver

'Red improver' ratings are assigned to seafood sources which have been assessed and rated 5 (red) due to significant environmental concerns
with one or more aspects of their management, capture or production, yet credible efforts to improve these issues have been agreed through a
Fisheries or Aquaculture Improvement Project – a FIP or an AIP - and work is underway. Such projects are normally publicly listed at
www.fisheryprogress.org. MCS wants to encourage environmental improvements in fisheries and fish farms, and so does not recommend avoiding
these sources, as we normally do for seafood rated 5 (red rated).

'Best choice' fish are rated 1 and 2, Fish to Avoid are rated 5.

This system has been developed by the Marine Conservation Society to help businesses and consumers choose the most environmentally
sustainable fish.

Rating 5

Rating 5 (red) is associated with fish to be avoided on the
basis that all or most of the criteria for sustainablilty
have not been met.